Differential immune responses of red deer (Cervus elaphus) following experimental challenge with Mycobacterium avium subspecies paratuberculosis

Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand; AgResearch Invermay, Dunedin, New Zealand

^* To whom correspondence should be addressed. Email: robma167{at}student.otago.ac.nz.

	Abstract

Immune responses of red deer (Cervus elaphus) that presented with different levels of paucibacillary pathology were profiled to detail immune changes during the progression of Johne's disease. Immune responses were monitored using an IgG₁ antibody ELISA, an IFN ELISA and flow cytometry. Animals in the study were divided into outcome groups after post-mortem according to disease severity. All animals mounted IgG₁ antibody and IFN responses to both vaccination and experimental challenge. The Map-specific IgG₁ antibody responses in the challenged group showed marked differences between infected and severely diseased animals. Slightly higher IFN responses were seen in infected animals when compared with severely diseased animals. No significant changes were seen in the phenotype of lymphocyte populations investigated. Vaccination with killed Map in mineral oil adjuvant reduced the level of severe disease however it obscured immunological differences between the infected and severely diseased groups. This suggests protection is not exclusively mediated via the presence of a Type 1 response and furthermore the presence of a Type 2 response is compatible with protection. These profiles provide information on the different immune processes in Johne's disease progression.